Florida Wastewater Practice Test

What causes classic sludge bulking in wastewater treatment?

1. Excessive chemical dosing

2. Young sludge

3. High temperatures

4. Low organic loading

The correct answer is: Young sludge

Classic sludge bulking in wastewater treatment is primarily caused by young sludge, which refers to the accumulation of microorganisms that have not yet attained the ideal age for optimal settling characteristics. Young sludge tends to have higher proportions of filamentous bacteria, which, if they proliferate excessively, can lead to the formation of a loose, fluffy mass that does not settle well. This poor settling ability is a key characteristic of sludge bulking, leading to difficulties in the separation of solids from liquids during the treatment process. In contrast, excessive chemical dosing can create conditions that may also affect settling but does not specifically lead to sludge bulking in the classic sense. High temperatures may influence microbial activity and settling properties, but they are not the direct cause of classic sludge bulking. Low organic loading can lead to reduced microbial activity and may result in clearer effluent but is not associated with the bulking phenomenon that occurs with young sludge. Thus, understanding the role of young sludge is crucial for managing and preventing sludge bulking in wastewater treatment processes.